As plastic materials become more and more widely used as replacements for metal, their incorporation into firearms is inevitable. Plastics have already been used in the manufacture of magazines for firearms for many years and have resulted in the issuance of patents, for example, U.S. Pat. No. 4,509,283, to Chesnut, Apr. 9, 1985. Additionally, plastics have been suggested and disclosed for use in other components of firearms such as a pistol grip as disclosed in U.S. Pat. No. 4,539,889, to Glock, Sep. 10, 1985. The Glock patent requires the molding of plastic around metallic pieces, thus, while the grip of the Glock pistol may be plastic, it still requires integral metal pieces to function. Additionally, there has even been a patent issued on a metal lined plastic barrel, U.S. Pat. No. 4,769,938 to Chesnut et al. Sep. 13, 1988.
Another well-known use of plastic materials and firearms can be seen in the current U.S. Army standard issue assault rifle, designated the M-16. In the M-16, the stock and forearm are made of a strong, light weight plastic material.
Nonetheless, it still remains worthwhile to provide a firearm which better utilizes plastic in the composition thereof. An important purpose of the present invention is to use plastic(s) wherever practicable in the firearm. The advantage of such use is clear, i.e., the weight of the forearm is decreased by the increased use of plastics. It is also an important aspect of the present invention that the firearm is provided with enhanced safety features that are both reliable and easy to use by the firearm user or shooter.
Typically a firearm contains one or more safety features to prevent unwanted firing thereof For example, U.S. Pat. No. 4,422,254, to McQueen, Sep. 27, 1983, discloses the use of a sear block, U.S. Pat. No. 4,208,947, to Hillberg, Jun. 24, 1980, discloses a hammer block and U.S. Pat. No. 4,282,795, to Beretta, Aug. 11, 1981, discloses a firing pin block.
Additionally, the fire control of most firearms involves the interaction between a trigger, a disconnect bar, a sear and a hammer. The forces required to make the appropriate interactions work are provided by various tension and compression springs. Unfortunately, such springs tend to provide a gradually increasing force through their operating range. Thus when such springs are used, for example, as the controlling force to remove a sear from a cocked hammer (i.e. trigger pull), it is necessary to provide an increasing pressure to counteract the spring force up to the touch off point (where the sear releases the hammer). While higher trigger pull makes for a safer firearm, the change in required force is often distracting. After gradually increasing the pressure on the trigger, an operator suddenly has a nearly complete loss of pressure which may result in over compensation and a missed shot.
The sear/hammer interface is another area in many existing firearms which is open to improvement. The interface is typically located proximate the axis of rotation of the hammer where the forces acting on the hammer to bias the hammer in a specific direction, are greatest. Thus, to resist the hammer biasing force, a greater sear counter force is required which obviously requires a greater trigger pull to overcome. Thus, there is a need for a firearm that is lightweight, safe to operate and requires a constant force to fire.